STATEN ISLAND, N.Y. -- A three-day electronic music festival on Randall's Island has been cancelled for Sunday by the NYPD beause of two fatal drug overdoses and close calls that sent four people to intensive care units.

Police are saying the deaths appear to be the result of MDMA, known commonly as Ecstacy or Molly.

Thousands of young people, including Staten Island college students from as far away as Albany and Binghamton, were headed to the concert when word came at 8:45 a.m. Sunday from police.

"Due to serious health risks, the Electric Zoo music festival on Randall's Island ... has been cancelled,'' stated an email from the department's Deputy Commissioner for Public Information. "The city recommended cancellation and the event promoters have agreed.

"During the first two days of the Electric Zoo music festival, two concert-goers have died and at least four others became critically ill and have been placed in intensive care at area hospitals,'' police said, adding that the "definitive causes of death have not yet been determined, however, both appear to have involved the drug MDMA (Ecstasy, or Molly).

"The Electric Zoo organizers have worked with city officials to reduce health risks at this event, but in view of these occurrences, the safest course is to cancel the remaining day of the event."

Electric Zoo 2013 is the fifth Electric Zoo event. Although the number of attendees has not yet been released for this year, last year's Electric Zoo drew more than 110,000.

Electric Zoo took to their official Twitter account to make the formal announcement at 9:14 a.m.

The festival was set to start at 11 a.m., and had attracted people from all over the country and the world. At the first two days of the festival, attendees brought flags from Ireland, Australia, Brazil, Israel and others.

THE PARTY DRUG

MDMA has seen a surge in popularity within the past few years.

The drug appeared on the club scene during 1980s and early 90s in the form of Ecstasy. Use declined when its reputation became tainted: The MDMA was being mixed with a plethora of other mystery ingredients, including methamphetamine, ketamine or cocaine.

The allure to Molly, which is short for "molecule," is that it is a "pure" form of Ecstasy, and that the user is only taking MDMA. However, in a 52-sample investigation by the DEA, it was reported that 30 were composed of 4-MEC, a synthetic stimulant, while the rest were a mixture of controlled and non-controlled substances.

Molly, which is taken for the euphoric feelings it gives its users, often has side effects that include teeth grinding, dehydration, chills and fever. It can also cause fatal seizures and hyperthermia.

"I'm beyond upset and livid, to say the least," said Margolis. "While I believe these two deaths due to drug use is extremely disheartening, it's very upsetting for the rest of us who put a lot of time and money into attending the festival."

Margolis also expressed concern the future events could be effected, particularly those planned for New York City.

YOUNG LIVES LOST

The victims have been identified as Jeffery Russ, 23, of Rochester, and Olivia Rotundo, 20, of Providence, R.I.

There were also reports that a 16-year-old female was sexually assaulted and that 31 arrests were made at the festival Friday evening and Saturday.

In July, a Midland Beach man died following a night out clubbing in Manhattan.

The 20-year-old, who attended a similar concert on Governor's Island that Sunday night, was taken by ambulance to New York Presbyterian Hospital in Manhattan, where he died about 10 p.m. the following day.

He reportedly had an extremely high fever and a family member speculated that it was the result of an overdose, possibly Molly or a similar drug.